Sodium Levels and Health

Sodium is an important element from the group of alkali metals, which is counted among the electrolytes (blood salts).In this context, sodium is the main cation of the extracellular fluid (fluid located outside the cell), along with chloride (Cl) and bicarbonate (HCO3). Up to 90% of all sodium is found there.It plays an important role in the body’s water balance along with potassium and chloride. The average daily sodium intake is circa 150 mmol.

The process

Material needed

  • Blood serum
  • 24 h urine

Preparation of the patient

  • Not necessary

Disruptive factors

  • None known

Normal values – serum (blood)

Standard values in mmol/l
1st week of life 133-146
1st month of life (LM) 134-144
<6 LM 134-142
6TH-12TH LM 133-142
> 1st year of life 134-143
Adults 135-145

Normal values – urine

Normal value in mmol/24 h 50-200

Indications

  • Suspicion of disturbances in water balance

Interpretation

Interpretation of elevated values (in serum; hypernatremia (excess sodium)).

  • Dehydration (lack of fluid) – hypernatremia (excess sodium) in hypervolemia or hypertonic dehydration; hematocrit ↑
    • Increased fluid losses – e.g., because of diarrhea (diarrhea), fever, excessive sweating, polyuria (increased urine output), stoma (stoma carrier), fistulae, burns
    • Decreased fluid intake
    • Renal diabetes insipidus – due toADH resistance (resistance related to antidiuretic hormone), nephrocalcinosis, chronic pyelonephritis (inflammation of the renal pelvis), cystic kidneys.
    • Central diabetes insipidus (ADH deficiency).
  • Hyperhydration – hypernatremia (excess sodium) in hypervolemia (total protein ↓); hematocrit ↓
    • Excessive saline intake:
      • Conn syndrome (primary hyperaldosteronism).
      • Seawater intoxication (drinking salt water).
      • Iatrogenic (e.g., infusion of hypertonic saline or sodium bicarbonate solution or penicillin salts containing sodium)
    • Increased sodium reabsorption:
      • Renal insufficiency – process leading to a slowly progressive reduction in renal function.
  • Drugs (with sodium-retarding effect).

Interpretation of decreased values (in serum; hyponatremia (sodium deficiency)).

  • Pseudohyponatremia (pseudonatremia deficiency): this is characterized by euvolemia caused by displacement of plasma water by, for example, rapid infusion of a hypertonic solution or high concentrations of lipoproteins and plasma proteinsOther causes are:
    • Hyperlipoproteinemia (see lipoproteins).
    • Hyperproteinemia (plasmocytoma, Waldenström’s disease).
  • Dehydration: (hyponatremia (sodium deficiency) in hypovolemia) or isotonic and hypotonic dehydrationCauses are:
    • Diarrhea (diarrhea)
    • Vomiting
    • Mineral corticoid deficiency (Addison’s disease)
    • Interstitial nephritis
    • Salt-losing kidney
  • Hyponatremia (sodium deficiency) in euvolemia.
    • Syndrome of inadequate ADH secretion SIADH) (synonym: Schwartz-Bartter syndrome) – there is an inappropriately high secretion of antidiuretic hormone (ADH; ADH excess) in relation to blood plasma osmolality; this leads to inadequate fluid excretion by the kidneys with the formation of highly concentrated urine; the result is hyperhydration (overhydration) with dilutional hyponatremia (“dilutional sodium deficiency”), which can lead to cerebral edema (brain swelling). Etiology (causes): paraneoplastic in approximately 80% of cases in patients with small cell lung cancer; other possible causes include:

      Symptoms: Nausea (nausea), loss of appetite, cephalgia (headache).

  • Hyperhydration (hyponatremia (sodium deficiency) in hypervolemia (total protein↓) (= “sodium dilution”):
    • ADH excess (SIADH; syndrome of inadequate ADH secretion).
    • Heart failure
    • Cirrhosis of the liver
    • Myocardial infarction (heart attack), acute
    • Nephrotic syndrome
    • Renal insufficiency (progressive reduction of renal function), acute and chronic.
    • When water intake exceeds the excretory capacity of the kidney.
  • Hypoosmolality and hyponatremia (sodium deficiency).
    • Chronic alcohol abuse or alcohol intoxication.
  • Medication
  • Increased need
    • Increased sweat loss after heavy physical activity.
    • Pregnant and breastfeeding women
    • Losses through the skin, as in extensive skin lesions or cystic fibrosis (high sodium concentrations in sweat).

1 Drugs that stimulate the release of antidiuretic hormone (ADH)2 Drugs that exogenously supply ADH3 Drugs that may potentiate the action of ADH4 Drugs that may cause hyponatremia (sodium deficiency) of unclear etiology (cause).

Additional notes

  • Hyponatremia (sodium deficiency, < 135 mmol/l) may be the cause of gait unsteadiness (gait disturbances) and falls in the elderly.It is classified based on serum concentration as follows:
    • Mild hyponatremia (sodium deficiency, serum sodium values between 130 and 135 mmol/l).
    • Moderate hyponatremia (sodium deficiency, 125 to 129 mmol/l).
    • severe hyponatremia (sodium deficiency, < 125 mmol/l).

    The prevalence (disease incidence) is approximately 2%.Symptoms can vary from mild and nonspecific to severe and life-threatening. Moderately severe symptoms are: Nausea without vomiting, headache, and confusion. Severe symptoms include vomiting, cardiorespiratory problems, seizures, somnolence, and coma.Patients with chronic hyponatremia (sodium deficiency) are notable for gait unsteadiness (gait disturbance) and cognitive deficits.Hyponatremia (sodium deficiency) is considered an independent risk factor for increased mortality (death rate) in cardiovascular and pulmonary disease; in liver cirrhosis, hyponatremia (sodium deficiency) is considered an extremely unfavorable prognostic marker

  • The normal requirement for sodium in women as well as men is 550 mg/d.